Here is one more book from the scholar of Ancient Indian Science, Dominik Wujastyc. It represents the most upto date study on Classical Indian sciences. Please check the google link below to brows the book.

I am wondering what kind of relations existed between Indus people and their neighbors. Such a geographically extensive civilization may have had relations, friendly or otherwise with the many civilizations they came across.

John McIntosh: See http://www.academicroom.com/article/boring-no-more-trade-savvy-indus-emerges - Archaeologists now realize that the Indus dwarfed its grand neighbors in land area and population, surpassed them in many areas of engineering and technology, and was an aggressive player during humanity's first flirtation with globalization 5000 years ago. The old notion that the Indus people were an insular, homogeneous, and egalitarian bunch is being replaced by a view of a diverse and dynamic society that stretched from the Arabian Sea to the foothills of the Himalaya and was eager to do business with peoples from Afghanistan to Iraq. And the Indus people worried enough about the privileges of their elite to build thick walls to protect them. “This idea that the Indus was dull and monolithic—that's all nonsense,” says Louis Flam, an archaeologist at the City University of New York who has worked in Pakistan.